Pretty much the full list is just those 2 things:
1) Trust and Safety
2) Better onboarding for new users
🤷🏿♂️
I mean, I can get more detailed than that, but everything really maps to those 2. The only 3rd category would be:
3) Reduce costs for running an instance / increase non-VC, non-Ads, non-domation ways of getting paid for running / moderating an instance
If it's too expensive to run an instance, that tends to encourage mega instances. It also silences some important voices.